The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Satisfaction with Rudd slipping: Newspoll

Kevin Rudd continues to lead Tony Abbott as preferred prime minister, but the opposition leader's personal approval rating is catching up, a new poll suggests.

The most recent Newspoll, published on Monday in The Australian, says Mr Abbott has narrowed the gap as preferred prime minister since the election campaign began from 14 points to nine points.

Newspoll says Labor's primary vote is down two points to 35 per cent while the coalition is up two points to 46 per cent and the Greens are also up two points to 11 per cent.

The coalition is ahead on 52 per cent to Labor's 48 per cent on a two-party preferred basis.

On the question of who would make the better prime minister, Mr Rudd maintained a lead over Mr Abbott with his support of 46 per cent, down from 47 per cent last week, compared with Mr Abbott's 37 per cent, up four points.

The poll, conducted over the weekend, puts Mr Rudd's satisfaction rate at 39 per cent, up from 38 per cent last week, and dissatisfaction at 48 per cent, up one point from 47 per cent last week, his highest since the leadership change.

Mr Abbott's satisfaction rate rose four points to 38 per cent as dissatisfaction fell six points to 52 per cent.